1. Technical Field
The present invention relates to an autonomous running control system for vehicle and the method thereof and more specifically to the control system and method of an unmanned vehicle which can be operated by finding a position by itself based on radio waves from satellites.
2. Related Prior Arts
In autonomous controlled off-road vehicles used for mowing lawn or grasses in golf courses, parks, gardens or other miscellaneous fields, techniques for finding correctly the position where they are located are important in autonomous running.
Among those techniques, Japanese Patent Application Laid Open No. Toku-Kai-Sho 63-247612 discloses a technique for finding a vehicular position by receiving a radio wave transmitted from a satellite and further No. Toku-Kai-Hei 2-132321 discloses a technique using a dead reckoning navigation method by which the location of a vehicle is estimated from a running distance and a running direction.
However, the former technique lacks an accuracy for positioning, when it is applied to an autonomous controlled vehicle which travels within a relatively narrow range, because of a clock error of the satellite and the receiver, a delay of radio wave caused by ionized layer, and a delay of radio wave affected by atmosphere.
Further, in the latter technique there is such a disadvantage that errors are accumulated with an increase of running distance.